The PI and her collaborators propose to continue their studies on the biochemical characterization of the lipids of Pneumocystis carinii (Pc). The long term goal of this project is to better understand the lipid biochemistry of this pathogen. To further the lipid studies, the PI has presented four specific aims in this current proposal. The first aim is: To examine the pathway and mechanisms by which cis-9,10-epoxy stearic acid (signature lipid) is synthesized by Pc, and to characterize the lipoxygenase (lipoxidase) enzyme activity. The second aim is: to analyze lipid modifications of purified major surface glycoprotein preparations isolated from Pc, identify the lipidated sites on the molecules, and examine whether these molecules contain inositol-lipid anchors. The third aim of the proposal is: To identify and characterize Pc sphingolipids in detail, to examine their biosynthesis, and to determine whether the organism releases long-chain bases, ceramides and/or fumonisns or fumonism-like sphingoid bases. Finally, the fourth aim is: To characterize the lipids of human-derived P.c. hominis focusing on Pc specific "signature" molecules.